Logic Analyser

From Arcade Tester AR81
Jump to: navigation, search

Overview

The Logic Analyser feature is only available on software issues 1.30 and above. AOS software must be 2.27 or above to run correctly.

When Version 1.30 software is installed, the lower function buttons have changed by removing the HELP button and installing a new button called LOGIC. Help can still be obtained by typing the AOS command *? in main test window.

By clicking the LOGIC button, a full 8 channels logic analyser is invoked. Note that on Testers with Issue 1.0 motherboards installed, only a single channel can be used as the hardware does not have the necessary pins exposed to allow the remaining channels. Issue 2.0 boards have a connector at the side for this purpose.

The Screen displayed is shown below.

Main

Channel 1 is connected to the probe input so by setting the probe to Digital before running the Logic Analyser, signals between 0 and 5V can be displayed and analysed. Note that the current system has a limitation of 690nS for sampling speed.

Selecting the Channels

To change how many channels are used and displayed, simply click the Channel buttons along the top of the screen. The selected quantity will be highlighted in red.

Channel

4 Channels selected


Selecting Trigger

The trigger allows the tester to collect data from either the first Logic High level or Logic Low level detected. This allows the data for the other channels to be referenced from that point. Note the trigger is only applied to Channel 1. (ie the probe input)

To select the trigger level, click either

Trigger OFF - No trigger is used, signals free running Trigger HI - Trigger set to HIGH. Sampling starts on first HIGH Trigger LO - Trigger set to LOW. Sampling starts on first LOW

The selected trigger is highlighted in RED if active. The next picture shows this in use.

Trigger

Setting the Trigger Level to HIGH.


Aquiring Data

To aquire data to process, first connect all the test clips or if only using single channel, place probe on point you wish to read. After this is done, Click the AQUIRE button in green. This will load the data and for all 8 channels into the tester. Once it is aquired, the data will be held until the next AQUIRE is done or T/DIV is used. TDIV is time per division and can be set as low as 0.69uS (690nS). Use the + and – buttons to vary the Sampling (division) time.

Once data is aquired, it will be displayed as follows.

Wave

Once the data is Aquired, it wont change unless either the TDIV buttons, The AQUIRE button or the AUTO button are clicked.

By clicking the display area ONCE with the mouse LEFT button, a reference marker line is placed on the screen and the time from the first sample is displayed. This is shown on next picture.

Aquire

By DOUBLE clicking the display area then a timing diagram will appear. This will start from the first logic state change to the left of the point clicked and finish at the next state change to the right. The time for this period is displayed along with all points for other channels if used. The LEFT most point is the REFERENCE line where all timings will start. This is based on the samples and is not affected by the PAN or other settings. Changing any settings will hide these times. The next picture shows the timing diagrams in use.

1 Channel Timing

Timing Diagrams for 1 Channel

4 Channel Timing

Timing Diagrams for 4 Channels

Changing the SPAN

The SPAN can be changed easily by clicking the SPAN+ or SPAN- buttons. By doing this the speed for updating can be affected as more data will be displayed. If the SPAN is reduced, the time to update the display is reduced too so a balance can be found where the pulse is displayed without too slow a update. The stored data will not change by doing this and hence a pulse train can be stretched or shrunk to suit the display. The next picture shows this.

Span

Span Changed to show more of the data


Changing the PAN

By clicking the < or > buttons in YELLOW, the data will be Panned from left or right. This means the start point will shift and all timings will change to RED to indicate an offset is now in place. The data will not be affected but using this feature, pulses that are off the display area can be shifted along.

The next picture shows the PAN in use.

Span

Changing the PAN.


Taking a Snapshot

The Tester can store an image of the Display Area containing all the traces of all the channels and the timing data when present.

This can be done simply by RIGHT clicking the mouse button any time during testing.

The resultant file is stored in /home/pi/Desktop/Images folder and the format is in xxxx.PS compatible with Postscript ©.


AUTO mode

The AUTO button when clicked will aquire data but continuously for a period of about 45 seconds. This allows Live data to be displayed. While this mode is running, no other changes can be made so the display should be set up beforehand.